Enteral nutrition vs. TPN

North American guidelines have recommended early enteral nutrition WITHOUT parenteral nutrition for caloric deficiency in the first seven days of critical illness. However, European guidelines have recommend parenteral nutrition as soon as possible to reach caloric & nutritional goals early after admission to the intensive care unit. There has been no high level evidence to support or refute either approach until recently. The EPaNIC (Early Parenteral Nutrition Completing Enteral Nutrition in Adult Critically Ill Patients) study was recently published in the New England Journal of Medicine (1). The EPaNIC investigators conducted a prospective randomized trial comparing 2312 early vs. 2328 late parenteral nutrition patients in a group of ICU’s in Belgium. Early parenteral nutrition patients received aggressive caloric and nutritional supplementation that was initiated over ICU days 1-3. The late parenteral nutrition group received enteral nutrition as tolerated but no parenteral nutrition to achieve full caloric intake until day #7. Patients in the late parenteral nutrition group had reduced length of stay, lower mortality (P=0.007), and lower hospital costs. This trial gives us high level evidence for the LATE addition of parenteral nutrition in critically ill patients.

Second, a major ARDS (Acute Respiratory Distress Syndrome) Network Trial—the OMEGA study– was recently published in JAMA (2, 3). The network conducted a phase 3 trial to study the efficacy of fatty acid/antioxidant supplementation in improving outcome in acute lung injury. 272 patients enrolled–143 randomized to Omega-3 fatty acid + antioxidant supplementation and 129 placebo. The supplement or control was given BID and continued through day 21. Patients received standard ARDS Network lung protective ventilation, glycemic control, and fluid management. The trial was halted after the 1st interim analysis. Ventilator-free days (primary endpoint) were fewer in the omega-3 fatty acid supplement group– suggesting no benefit and possible harm. A trend toward higher mortality was seen in the supplement group as well. The therapy caused a biologic effect seen in elevated serum fatty acid levels. However, inflammatory markers, ventilatory parameters, and outcome (ventilator-free days) did not improve. There was insufficient power to determine harm from omega-3 supplementation.

In conclusion, in January 2012, the best evidence supports delayed parenteral nutrition in critically ill patients and no benefit for omega-3 rich enteral feeding in acute lung injury.